a) Field of the Invention
This invention relates to a stereomicroscope variable in magnification in which many units are arbitrarily mounted and a plurality of observers can make observations at any angle.
b) Description of the Prior Art
In recent years, precision work in small areas, such as fine working and operations, has come to be largely done. Hence, stereomicroscopes through which fine areas can be viewed and three-dimensional positions are secured, are provided as its effective means. Additionally, since cases has been increasing where plural observers must operate at the same time due to the precision work, it is desired that they can observe images with substantially the same magnification and stereoscopic visibility. There is also the improved demand for the attachments of apparatus using variable magnification optical systems, such as photographic devices, TV cameras, and laser devices, to the stereomicroscopes.
The conventional stereomicroscopes each have usually two or more variable magnification optical systems which are the same as one another. Hence, to enable plural observers to make observations, some of the stereomicroscopes are such that, as set forth in Japanese Utility Model Preliminary Publication No. Sho 60-1110 by way of example (FIGS. 1 and 2), optical paths arranged in a pair are each split into two so that the observers face to each other for observation. FIG. 1 is a side view showing the entire optical system of this prior art and FIG. 2 is a perspective view of its essential part, in which reference numeral 1 represents an objective lens used common to the optical paths of a bilateral optical system, 2 variable magnification optical systems, 3 beam splitters, 4 reflecting prisms, 5 optical path deflecting prisms, 6 imaging lens, 7 Porro prisms, and 8 eyepieces.
Further, some of the stereomicroscopes are such that, for example, as set forth in Japanese Patent Preliminary Publication No. Sho 56-144410 (FIGS. 3 and 4), the pair to the optical path is split and a pupil is divided at a position of the pupil relayed for a stereoscopic view. FIG. 3 is a front view showing the entire optical system of this prior art and FIG. 4 is a plan view of its pupil dividing section. In these figures, reference symbol P denotes a glass block for adjusting the optical path lengths of the bilateral optical system, numerals 9 and 9' relay lenses, 10 an image rotator, and 11 a pupil dividing mirror, in which like reference numerals indicate the members having like functions with those shown in FIGS. 1 and 2.
Others of the stereomicroscopes are such that, for example, as stated in Japanese Patent Preliminary Publication No. Sho 61-172111 (FIGS. 5 and 6), three or more variable magnification optical systems are incorporated therein. FIG. 5 is a front view showing the entire optical system of one embodiment of this prior art and FIG. 6 is a plan view of the essential part thereof, in which reference numeral 12 and 12' denote imaging optical systems including imaging lenses and 13 a mirror.
In any of the prior art mentioned above, however, the split of optical paths for the stereoscopic view, that is, for making separate beams of light incident on the eyes of each observer, is performed by providing the variable magnification optical systems in a pair directly behind a common objective lens, so that the arrangement of a microscopic optical system is complicated. Such an optical system has encountered the problems that, in order to enable a number of people to make observations and photographic and TV devices to be mounted, other prisms and variable magnification optical systems are inevitably added and consequently, the structure of the microscope will become very complicated and bulky. Further, there have been the problems that, to change the directions in which plural observers see through the microscope, the whole of the variable magnification optical systems must be moved and rotated, so that the structure becomes more complicated with difficult adjustment. Moreover, the problems have arisen that the use of a plurality of variable magnification optical systems makes it liable to produce an error of adjustment due to the difference in magnification between the images of the bilateral optical system to be observed and develop eyestrain attributable thereto.
Also, an optical system is available in which a pair of eyepieces is disposed through reflecting members behind a single objective lens for the stereoscopic view. In the optical system proposed, for example, by Japanese Patent Preliminary Publication No. Sho 61-61118 shown in FIG. 7, by changing the angles of mirrors 2a, 3a and 2b, 3b in pairs, the courses of rays of light are altered from the optical paths indicated by the broken lines to those by the chain lines and the internal inclination angles of the bilateral optical path are changed accordingly so that correct stereoscopic visibility is secured. This example, however, falls to show the combination with the variable magnification optical system.